By Mitch DeCaire, Cogiscan, Inc., Bromont, Quebec, Canada In recent years, the increased demand for material traceability has been driven by competitive pressures for improving product quality, while also reducing cost. Traceability requirements, once limited to high reliability applications, such as automotive, aerospace and medical, are rapidly becoming a necessity in other sectors including data communications, telecom, and high-end computing. Some factors driving these demands include; outsourcing, product recalls, liability, lead-free and lean manufacturing. While demanding traceability from their EMS providers, OEMs are placing an increased emphasis on data integrity. After all, what use is traceability if the data is not captured completely and accurately? This is motivating assemblers to change from manual scanning operations and open-loop systems to smart material detection, in an effort to error-proof their systems. Safeguards are being incorporated to automatically prevent production unless the specified traceability data has been successfully recorded.

100 Percent Data Capture
A traceability solution is only as good as the data that goes into it. For this simple reason, sources of data loss should be eliminated wherever possible. A common source of data loss comes from the need to capture each PC board serial number at strategic points throughout the assembly process. In such applications, the PC board serial number is typically marked by a barcode or 2D data matrix symbol. The PC board S/N can be missed due to quality issues associated with the creation and placement of the identifier, or if scanners along the line are not properly adjusted during product changeover.

Product Flow Control can be implemented to control the SMEMA handshake between conveyors and machines at each PC board scan point, and prevent a PC board from transferring downstream unless the product serial number has been successfully captured. The mechanisms deployed for product flow control can also be used to halt production when the system detects a route step error, or a product that failed to pass a prior test or inspection step.

Manual Scans
Another common error source stems from manually scanning barcodes while materials (components, stencils, solder paste, etc.) are placed at specified locations along the production line. Automated material detection technologies, often termed smart technologies, are available to prevent such errors. For example, Radio Frequency Identification (RFID) is an emerging material detection and tracking technology that is garnering much attention.

Tape feeders for an SMT placement machine represent a practical application for RFID. The typical PC board assembly factory has made a significant investment in a large number of feeders for different types of components and different types of machines. RFID tags can be attached to each feeder, regardless of feeder type or brand name, to convert standard feeders into "Smart" feeders.

RF antenna arrays can be installed within a placement machine's feeder banks, and also within off-line changeover banks and feeder storage racks. This enables tracking of feeders, including reels of components on the feeders, throughout the entire factory. This leads to a more efficient production operation by making sure that the required feeders are available when needed, and time is never wasted searching for them.

Tags on Feeders
The use of RFID tags on feeders enables automatic validation of the feeders and reels on the placement machine, to prevent assembly defects, while automatically collecting accurate component traceability data during machine setup and replenishment. The use of RFID technology can be extended beyond the placement machines, to any other type of assembly station. For example, RFID can be used to validate that the correct stencil and solder paste are present at a screen printer, or that the correct bin of components resides at a manual assembly station.

The most robust traceability systems integrate product flow control with automated material and tooling detection at multiple assembly stations. This ensures that all specified materials are recorded and validated, with minimal human intervention, before the product proceeds to the next assembly step or station.

To fulfill customer requirements, material traceability systems must ensure 100 percent data capture and accuracy. This reinforces the importance of eliminating the risk of human error wherever possible. A robust traceability system is one that can automatically ensure 100 percent data capture, while preventing production unless the presence of all required materials is confirmed throughout each assembly step.